I have used the free version on one of my projects and It works really
well. I love the back end admin interface of the plugin. I am giving it four stars because in my opinion it still lacks the possibility of translating the front end validation messages, which I consider very important when developing a multilingual website. Other than that it is one of the best form building plugins that I have used so far.

First of all thanks for your quick response. As I didn´t find this information in wordpress.org I went about translating these messages in the plugin´s core javascript files, which I know isn´t the best way to do it.

For me, your solution is much better than the one I did the only downside It may have is that not everybody can do it especially those with no coding knowledge. I still think that it would be perfect if you could implement the possibility of translating and customizing all the validation messages right from the Visual Form Builder´s admin panel.